1. Field of Invention
An independent suspension especially, but not exclusively for wheeled vehicles.
2. Prior Art
The difficulties in achieving the optimum performance for the suspension of wheeled vehicles has resulted in numerous inventions and devices, which employ a wide range of strategies to reach that performance. Because of this, a condensed summation of the prior art is used, although the patent search extended much beyond the presented material. These patents represent key points in the suspension of wheeled vehicles, and therefore, a good basis for comparison with the flex arm suspension.
U.S. Pat. No. 4,973,070, 1990, F. Menichini, E. Perri.
U.S. Pat. No. 4,969,661, 1990, A Omura, M. Kikkawa.
U.S. Pat. No. 4,968,056, 1990, T. Haraguchi.
U.S. Pat. No. 4,966,385, 1990, T. Iwasaki, H. Shimonura.
U.S. Pat. No. 4,964,651, 1990, K. Kubo.
U.S. Pat. No. 4,842,295, 1989, G. Hawkins.
U.S. Pat. No. 4,695,073, 1987, C. Pettibone, D. Berry.
U.S. Pat. No. 4,556,235, 1985, F. Giebel.
U.S. Pat. No. 4,556,234, 1985, F. Mahnig, H. Meister.
U.S. Pat. No. 4,530,514, 1985, H. Ito.
U.S. Pat. No. 4,529,223, 1985, T. Kijima, J. Maebayashi.
U.S. Pat. No. 3,913,932, 1975, C. Guerriero, D. Hayward.
U.S. Pat. No. 3,689,102, 1972, O. Granning.
U.S. Pat. No. 3,603,422, 1971, E. Cordiano.
U.S. Pat. No. 3,603,421, 1971, T. Maeda, S. Miyata.
To help demonstrate how the flex arm suspension differs from the above suspensions, and to facilitate the explanation, a review of terms will be given and used again without explanation. Differences from the explained terms will be dealt with as they come up.
A-frame, arm, wishbone are terms that when referring to suspensions, accomplish a very similar task. What these devices do is connect the spindle assembly, sometimes referred to as a knuckle, or kingpin, depending on the type of suspension, to a frame, chassis, or suitable mounting point on the wheeled vehicle. The spindle is were the wheel is mounted. The arms, and their various permutations, usually rotate or pivot about the point where they mount. This allows the wheel to move with relative independence to the vehicle to which it mounts. All this is fairly obvious, but their limitations are not obvious. It must be kept in mind throughout this discussion, that arms, whatever their form, limits the path on which the wheel can travel. Multi-link is a term used to describe an increasingly wider range of suspension devices. For the most part, a suspension employing a multi-link design is one that is attempting to overcome the shortcomings of the arm, A-frame, or wishbone. Multi-links are usually comprised of rigid bars and flexible bushings, designed in such a fashion as to change the attitude of the wheel as it rotates about the arm, A-frame, or wishbone mounting point. Camber is a term used to describe the angle the wheel takes relative to the driving surface. Camber often changes as the arms rotate about their mounts. Centerline is an imaginary line that runs down the middle of the wheeled vehicle in a direction parallel to the rotation of the wheels. Toe in and toe out are terms used to describe the angle the wheel takes in relation to the centerline of the vehicle. Toe in is the wheel rolling in towards the centerline, and toe out is the wheel rolling out away from the centerline. Neutral toe is the wheel rolling parallel to the centerline. Toe can also be used to describe the deviation a wheel takes in relation to the ideal line needed to make a turn. This type of toe is an important consideration in steering, but outside of steering considerations, toe is usually a negative, which often results from flexible bushings mounted at critical points, or because of ball joints. Ball joints are the connection point between the knuckle, or spindle assembly, for some suspensions. Ball joints allow 360 degree rotation about the point where they mount on the arm. While this provides some advantages for the suspension, ball joints can allow toe in or toe out.
The arms of a suspension are mounted in various positions relative to the centerline of the vehicle. The A-frame, and wishbone style arms are mounted perpendicular to the centerline. The trailing arm suspension is mounted parallel to the centerline. The semi-trailing arm suspension is similar to the trailing arm, but is usually mounted at some angle off of parallel to the centerline.
These, of course, are generalities. Now, specifics can be discussed.
U.S. Pat. No. 4,973,070, 1990, F. Menichini, E. Perri, is a suspension designed to respond to the driving surface. The difference here is that this is an operative system. The flex arm suspension adjusts to the driving surface by responding to the forces created by moving over the driving surface. There is no need for outside manipulation in the flex arm suspension. Also, there is no flex arm assembly in the Menichini, Perri design. While there may be some similar intent in the concepts, the execution of the design is completely different.
U.S. Pat. No. 4,969,661, 1990, A. Omura, M. Kikkawa, is a multi-link design. As is typical with nearly all multi-link designs, the multi-link system attempts to correct wheel position problems that result from the limits of the arm movement. The A. Omura, M. Kikkawa design is no exception. The A-frame style arm sweeps out its arc, while the multi-links attempt to adjust the changing angle the wheel must make. The flex arm suspension does not need to sweep out an arc. A multi-link design is not needed to correct the changing angle of the wheel in the flex arm design because the wheel is not limited to one path. The arm design in the Omura, Kikkawa suspension limits the path the wheel can take, and so, is in need of a multi-link designed system. In this suspension, again, there is no flex arm assembly, and no opposing spring/strut design as in the flex arm suspension.
U.S. Pat. No. 4,968,056, 1990, T. Haraguchi, is an even more obvious A-frame design. It too employs a multi-link system. The same shortcomings expressed for the Omura, Kikkawa design apply here.
U.S. Pat. No. 4,966,385, 1990, T. Iwasaki, H. Shimonura is a double wishbone design. This employs the light weight nature of a wishbone design with the adjusting powers of a multi-link system. Again, the arms sweep out arcs that limit the path the wheel can travel. The multi-link attempts to adjust the wheel as the wishbones move through their arcs. There is no flex arm assembly in this design, and no opposing spring/strut design.
Nearly the same concept as above is employed in U.S. Pat. No. 4,964,561, 1990, K. Kubo. This is a wishbone design which also employs a multi-link system. The difference noted above for the Iwasaki, Shimonura design apply in this case.
U.S. Pat. No. 4,842,295, 1989 G. Hawkins, is a multi-link suspension system. Although this design differs somewhat from the designs above, the theme is obvious by now. This design also lacks the flex arm assembly, and the opposing spring/strut design.
The reason the above patents are discussed is because they are similar to the flex arm suspension in one respect. These designs all have arms, is some fashion or other, perpendicular to the vehicle centerline. The flex arm suspension is mounted in a similar fashion, but has the flex arm assembly, and the opposing spring/strut design. These above designs do not. The Menichini, Perri suspension demonstrates a version of suspension correction. The flex arm suspension is self correcting. The Menichini, Perri design needs an outside operator to correct it. The other suspensions use multi-link systems to adjust the wheel as it travels through its arc. The flex arm does not need multi-link adjustment. The flex arm design allows numerous paths, allows travel in a straight line, and under straight ahead driving conditions, is in no need of correction to maintain optimum wheel contact with the driving surface. And in essence, that is what all these devices and designs attempt to do. The point is, that the flex arm suspension is more than a refinement of the prior art. This is a new concept, executed in a fashion that makes it different from all other suspension design. To further underscore this, the flex arm design will now be compared to suspensions that differ even more than the previous examples.
U.S. Pat. No. 4,695,073, 1987, C. Pettibone, D. Berry is a design that employs a trailing arm suspension with adjustable camber and toe in. The advantages of a trailing arm design is that under normal driving conditions, this design can give response nearly perpendicular to the driving surface. The flex arm suspension does this as well. This particular design allows for adjustment of camber and toe in. This differs from the flex arm suspension. The flex arm suspension makes no provisions for camber adjustments, or toe adjustments. The kingpin/spindle assembly is mounted on opposite sides by the arm assemblies. This does not allow the wheel to twist in a manner that will cause toe in or toe out. Toe in or toe out adjustments are not needed on the flex arm suspension because toe does not occur. Camber adjustments are not needed either, because camber changes occur only at the very extremes of the flex arm response. The Pettibone, Berry design is very different from the flex arm design, and those of the wishbone and A-frame design, and yet, the flex arm can accomplish the perpendicular to the driving surface response that is considered a feature of the trailing arm design. Even though the flex arm eliminates changing camber and unwanted toe, there is no reason why the kingpin/spindle assembly could not be designed to incorporate such features as adjustable camber or toe. Features, such as passive steering, or straight line braking, or even active steering, which benefit from a certain amount of toe, are not contradictory to the flex arm design. Straight line trackability, or crosswind stability, which benefit from a slight camber, are not contradictory to the flex arm design. There are advantages to camber and toe, but only in specific situations, and only in controlled and measured amounts. Where the flex arm suspension differs is in the fact that the negative aspects of toe changes and camber changes are eliminated, thus eliminating the need to design around, or correct flaws that are inherent in so many other suspension designs. Clearly, the Pettibone, Berry suspension system is different from the flex arm design, but the advantages their design offers are matched, or can be matched, and as will be shown, can even be surpassed by the flex arm suspension.
U.S. Pat. No. 4,556,235, 1985, Giebel is a multi-link design. This design addresses the problem of toe in and toe out. The multi-link system in this design is designed to correct the problems of toe in and toe out. Because the kingpin/spindle assembly of the flex arm suspension is supported on both sides, top and bottom by the flex arm assemblies, the wheel will not twist about the kingpin/spindle assembly in a fashion that will cause toe in or toe out. Also, there are no flexible bushings at critical points that may cause the flex arm suspension to toe in or toe out. Unlike the Giebel design, no multi-link design is needed to correct toe in or toe out.
U.S. Pat. No. 4,556,234, 1985, F. Mahnig, H. Meister is a patent on an arm design. This arm does not possess the three jointed arm that the arm assemblies of the flex arm suspension does.
U.S. Pat. No. 4,530,574, 1985, H. Ito, is a trailing arm suspension. This is not a multi-link suspension, but the design does correct toe in. This differs from the flex arm suspension in that the flex arm suspension does not allow toe in or toe out. The Ito suspension possess dynamic toe correction. It changes toe by altering the wheel camber. The flex arm suspension does not generate camber changes through most of its travel, so on that point, these two suspensions differ. The Ito trailing arm design does not possess the flex arm design or the opposing spring/strut design.
U.S. Pat. No. 4,529,223, 1985, T. Kijima, J. Maebayashi, is a semi-trailing arm suspension. This particular design does employ a strut and spring design, namely, a McPhearson strut with a coil. This differs from the flex arm spring/strut design in the fact that the McPhearson strut works with the spring, not in opposition to it. The flex arm suspension uses countering balances of springs against spring loaded struts to produce its dynamic range of motion while preserving the angle of the wheel relative to the driving surface. Also, there is no flex arm design incorporated in the semi-trailing arm.
U.S. Pat. No. 3,913,932, 1975, C. Guerriero, D. Hayward employs a leaf spring and strut style suspension, and this too differs considerably from what has been discussed. This suspension clearly has no flex arm framework, or suspension arm in the typical sense. On that basis alone it is completely different from the flex arm suspension. Also, the strut and spring design does not work in opposition. The struts in the Guerriero, Hayward design bear the vehicle load, and dampen shock. For most practical purposes, the upper strut and the upper leaf springs in the flex arm suspension would share the load bearing duties. The leaf spring in the Guerriero, Hayward design is largely responsible for governing the suspension travel. This is true for the flex arm suspension as well. The leaf springs in the flex arm suspension, however, regulate the suspension travel by regulating the flex arm assembly framework. There is no such framework in the Guerriero, Hayward design, and no opposing spring/strut design. The leaf spring in this particular design connects between the two wheels, and to a degree acts as a a flexible arm, but it is not a flex arm in the sense that the leaf spring is still limited to a single arc that it can sweep out. Also, the connection by the leaf spring between the two wheels means this is not an independent suspension. The flex arm suspension is an independent suspension.
U.S. Pat. No. 3,689,102, 1972, O. Granning is a trailing arm design suspension. Again, there is no flex arm design, and no opposing spring/strut design. This design differs from the flex arm suspension on almost all points.
U.S. Pat. No. 3,603,422, 1971, E. Cordiano, is also a trailing arm suspension. This particular suspension features static toe in control. The differences of the trailing arm suspension have already been made clear. They apply here. The static toe in control is adjustable in this particular suspension. While this concept is not contradictory to the flex arm suspension, toe in or out control is not a feature of the flex arm suspension. The wheel in the flex arm suspension is held parallel to the vehicle centerline, and toe is not allowed by the flex arm assemblies. These two suspensions also differ on this point.
U.S. Pat. No. 3,603,421, 1971, T. Maeda, S. Miyata is a semi-trailing arm suspension. Again, no flex arm design, and no opposing spring/strut system is incorporated. This design does allow for the changing of camber as the arms sweep through its arc, and on that point, differs from the flex arm suspension. The toe control of this type of suspension, or of any suspension has been addressed, and so, this suspension differs from the flex arm suspension in that respect.
The obvious points as to where the flex arm suspension design differs from other suspensions is in the flex arm itself, and the opposing spring design. This is a clear cut difference over the prior art. The results of this design also goes further to separate it from the prior art. The presented cases were just a summation of the research into the prior art. The research was much more extensive, but all cases reviewed proved to be substantially different from the flex arm suspension in both design, and overall results that could be achieved.